Gunde Ziegelberger

Validity and use of the UV index: report from the UVI working group, Schloss Hohenkammer, Germany, 5-7 December 2011.

Abstract The adequacy of the UV Index (UVI), a simple measure of ambient solar ultraviolet (UV) radiation, has been questioned on the basis of recent scientific data on the importance of vitamin D for human health, the mutagenic capacity of radiation in the UVA wavelength, and limitations in the behavioral impact of the UVI as a public awareness tool. A working group convened by ICNIRP and WHO met to assess whether modifications of the UVI were warranted and to discuss ways of improving its effectiveness as a guide to healthy sun-protective behavior. A UV Index greater than 3 was confirmed as indicating ambient UV levels at which harmful sun exposure and sunburns could occur and hence as the threshold for promoting preventive messages. There is currently insufficient evidence about the quantitative relationship of sun exposure, vitamin D, and human health to include vitamin D considerations in sun protection recommendations. The role of UVA in sunlight-induced dermal immunosuppression and DNA damage was acknowledged, but the contribution of UVA to skin carcinogenesis could not be quantified precisely. As ambient UVA and UVB levels mostly vary in parallel in real life situations, any minor modification of the UVI weighting function with respect to UVA-induced skin cancer would not be expected to have a significant impact on the UV Index. Though it has been shown that the UV Index can raise awareness of the risk of UV radiation to some extent, the UVI does not appear to change attitudes to sun protection or behavior in the way it is presently used. Changes in the UVI itself were not warranted based on these findings, but rather research testing health behavior models, including the roles of self-efficacy and self-affirmation in relation to intention to use sun protection among different susceptible groups, should be carried out to develop more successful strategies toward improving sun protection behavior.

Research recommendations toward a better understanding of the causes of childhood leukemia

A small expert group met in conclave in July 2010 to define a long-term strategic research agenda toward further clarification of the etiology of childhood leukemia (CL). The motivation and invitation for this project came from the German Office for Radiation Protection (BfS) because radiation experts have been puzzled for some time by epidemiological findings of an increased incidence of CL near German nuclear facilities,1 as well as by a statistical association with exposure to residential low-frequency magnetic fields.2 Both findings are difficult to explain given the current knowledge of the biological mechanisms of ionizing or non-ionizing radiation, as both types of exposure deposit far too little energy in cellular DNA and other likely targets to be considered directly causative. A previous workshop on risk factors held in May 20083 and a follow-up meeting led to the conclusion that understanding of the causes of CL development requires a broadened, interdisciplinary approach.

Childhood leukaemia risks: from unexplained findings near nuclear installations to recommendations for future research.

Recent findings related to childhood leukaemia incidence near nuclear installations have raised questions which can be answered neither by current knowledge on radiation risk nor by other established risk factors. In 2012, a workshop was organised on this topic with two objectives: (a) review of results and discussion of methodological limitations of studies near nuclear installations; (b) identification of directions for future research into the causes and pathogenesis of childhood leukaemia. The workshop gathered 42 participants from different disciplines, extending widely outside of the radiation protection field. Regarding the proximity of nuclear installations, the need for continuous surveillance of childhood leukaemia incidence was highlighted, including a better characterisation of the local population. The creation of collaborative working groups was recommended for consistency in methodologies and the possibility of combining data for future analyses. Regarding the causes of childhood leukaemia, major fields of research were discussed (environmental risk factors, genetics, infections, immunity, stem cells, experimental research). The need for multidisciplinary collaboration in developing research activities was underlined, including the prevalence of potential predisposition markers and investigating further the infectious aetiology hypothesis. Animal studies and genetic/epigenetic approaches appear of great interest. Routes for future research were pointed out.

A Closer Look at the Thresholds of Thermal Damage: Workshop Report by an ICNIRP Task Group.

AbstractThe International Commission on Non-Ionizing Radiation Protection issued guidelines in 1998 for limiting public and occupational exposure to radiofrequency electromagnetic fields (100 kHz to 300 GHz). As part of the process of updating this advice, a 2‐d workshop titled “A closer look at the thresholds of thermal damage” was held from 26–28 May 2015 in Istanbul to re-examine the thermal basis of the guidelines and to provide further information on heat-related effects and thresholds of thermal damage. Overall, the workshop provided much useful information relevant to revision of the guidelines. Participants indicated that the effects of heating from radiofrequency fields are consistent with those from other sources, and that the information derived from those studies can be applied to radiofrequency-induced heating. Another conclusion was that absolute temperature of tissues was more important for thermal damage than temperature change. The discussion suggested that the 6‐min averaging time used in international guidelines was valid for whole-body exposures but with a large uncertainty: 30 min may be a more appropriate averaging time for localized exposures, and less than 1 min for implanted medical devices. The duration of whole-body radiofrequency exposure is a critical parameter that often determines the effect threshold, but this will be affected by other, ongoing thermoregulation, which is dependant on many factors. The thresholds for localized radiofrequency exposure were difficult to determine because of the potential range of exposure conditions and the possibility of radiofrequency-induced local hotspots. Suggestions for future dose metrics and further research were discussed and are included in this report.

Response by ICNIRP to the comments of Gowland and Glover.

Dear Editors: GOWLAND AND Glover expressed dismay that their 2007 paper (Glover et al. 2007) had been used by ICNIRP in setting limits on exposure to electric fields induced by movement of the human body in a static magnetic field and by time-varying magnetic fields below 1 Hz (ICNIRP 2014). As Gowland and Glover correctly state, their study was the first in the field, and there is a clear need for more data. At the time of writing the guidelines, their study was the only research providing useful information for setting guidelines. Important new findings from two studies were recently published (Mian et al. 2013; Glover et al. 2014), but they do not provide sufficient reason for fundamental changes in the exposure guidelines. The main target of the criticism is the protection against vertigo by limiting the change of the magnetic flux density in order to limit slowly varying induced electric fields. This was indeed an important aspect, but it was not the only one taken into account. The guidelines explicitly state that “.... given the possibility of direct magnetic fields on the body, it is important to restrict both the static magnetic flux density (B) and the maximum change of the magnetic flux density (Δ B) experienced by the body during movement” (ICNIRP 2014). Given the present state of knowledge, to which Gowland and Glover have contributed much, it is best to assume that both the direct Lorentz force and electric field effects contribute to motion-induced vertigo. The new findings have increased the likelihood that the Lorentz force on ionic currents in the vestibular organ explains the vertigo effect, but other mechanisms and particularly those due to the induced electric field still cannot be neglected. It has been well known for 150 years that the electric field induced by the galvanic current in the vestibular system causes vertigo. The new research findings indicate that the balance system in humans seems to react more to the change of the magnetic flux density than to the magnetic field itself. It should be noted that the new ICNIRP guidelines should be applied together with the guidelines for static magnetic fields (ICNIRP 2009). Therefore, ICNIRP recommends restricting both the static magnetic flux density and its change during movement. This does not contradict the Lorentz model. A relevant issue is the relatively short integration time of 3 s, during which the change of the magnetic flux density should not exceed 2 T. In a 7 T field, it would be possible to move into the field in 10 s in order to comply with the guidelines, while the study of Glover et al. (2014) indicates that the adaptation time constant would be approximately 40 s or even longer. However, it is important